The present invention concerns a drive apparatus for a magnetic tape gripped between two rollers, simultaneous rotation of which provides the drive for said tape, the apparatus including a drive roller rotatable about a first axis and providing the energy required for driving the tape, and a pinch roller, rotatable about a second axis substantially parallel to the first and ensuring grip of the tape.
Such gripping drive apparatus for tape are well known in the field of magnetic recording. An example of such is given in U.S. Pat. Nos. 3,907,230 by the same inventor.
These known apparatus, in which the tape is gripped directly between the drive roller and the pinch roller, present a problem which, although without serious consequences in normal use, can be very troublesome in special applications.
More particularly, when the passage of the tape involves frequent forward and reverse shuttle movements or stops and starts, the tape is subject to deflections in height on the pinch roller, that is to say it rises or falls according to the direction of rotation of the roller.
At normal temperatures, the deflection in height may be relatively small, for example of the order of a tenth of a millimeter.
Nevertheless, the deflection increases when the temperature falls, to the point of reaching typically six tenths of a millimeter at -40.degree. C.
When the deflections reach such levels, which are no longer at all negligible in comparison with the width of the recording tracks corresponding to data recorded on the tape, the result is, in reading the data, a weakening of the output signals which is at least inconvenient, and occasionally even unacceptable.
Against this background, an object of the present invention is to provide a magnetic tape drive only introducing a negligible tape deflection, even when used in a shuttle regime and at relatively low temperatures, of the order of -40.degree. C.